U.S. patent number 11,214,004 [Application Number 17/050,924] was granted by the patent office on 2022-01-04 for build compartment with self-sealing design.
This patent grant is currently assigned to FREEMELT AB. The grantee listed for this patent is Freemelt AB. Invention is credited to Ulf Ackelid.
United States Patent |
11,214,004 |
Ackelid |
January 4, 2022 |
Build compartment with self-sealing design
Abstract
The present invention relates to a build compartment used in 3D
printing systems based on powder beds. The build compartment is the
volume in a 3D printing apparatus where 3D objects are formed by
successive consolidation of thin layers of powder. The build
compartment is designed with at least two vertical wall structures
movable in relation to each other. The movable wall structures are
at least partly overlapping in the movable direction, providing
self-sealing for a variable volume for enclosing powder. Contrary
to other available designs, this solution does not need a
compressible sealing material, for example an elastomer, a textile
felt or a braided rope, to prevent powder leakage from the build
compartment. The advantages are more reliable sealing and no risk
of contamination of the powder by debris from sealing material.
Inventors: |
Ackelid; Ulf (Gothenburg,
SE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Freemelt AB |
Molndal |
N/A |
SE |
|
|
Assignee: |
FREEMELT AB (Molndal,
SE)
|
Family
ID: |
1000006031884 |
Appl.
No.: |
17/050,924 |
Filed: |
April 25, 2019 |
PCT
Filed: |
April 25, 2019 |
PCT No.: |
PCT/EP2019/060622 |
371(c)(1),(2),(4) Date: |
October 27, 2020 |
PCT
Pub. No.: |
WO2019/207049 |
PCT
Pub. Date: |
October 31, 2019 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
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US 20210229354 A1 |
Jul 29, 2021 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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62663282 |
Apr 27, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C
64/25 (20170801); B29C 64/153 (20170801); B29C
64/255 (20170801); B29C 64/35 (20170801); B29C
64/295 (20170801); B33Y 30/00 (20141201) |
Current International
Class: |
B33Y
30/00 (20150101); B29C 64/255 (20170101); B29C
64/35 (20170101); B29C 64/153 (20170101); B29C
64/25 (20170101); B29C 64/295 (20170101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102009020987 |
|
Nov 2010 |
|
DE |
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2 926 923 |
|
Oct 2015 |
|
EP |
|
3 480 000 |
|
May 2019 |
|
EP |
|
2 503 215 |
|
Dec 2013 |
|
GB |
|
WO-2005/025780 |
|
Mar 2005 |
|
WO |
|
WO-2017/054859 |
|
Apr 2017 |
|
WO |
|
WO-2018/210521 |
|
Nov 2018 |
|
WO |
|
WO-2019/020340 |
|
Jan 2019 |
|
WO |
|
Other References
English translation of DE 102009020987. cited by examiner .
U.S. Appl. No. 17/257,100, filed Dec. 30, 2020, Ulf Ackelid. cited
by applicant.
|
Primary Examiner: Theisen; Mary Lynn F
Attorney, Agent or Firm: Faegre Drinker Biddle & Reath
LLP
Claims
What is claimed is:
1. An apparatus for manufacturing a three-dimensional object from
powder, comprising: a build compartment having a floor and at least
two wall structures movable in relation to each other, said wall
structures are at least partly overlapping in the movable
direction, providing a variable volume for enclosing powder,
wherein the floor is connected to at least one of said at least two
wall structures in such a way that a plane normal to the movable
direction intersects the floor and another of said at least two
vertical wall structures.
2. The apparatus according to claim 1, where said at least two wall
structures are vertical wall structures.
3. The apparatus according to claim 1, where said at least two wall
structures are inner and outer wall structures.
4. The apparatus according to claim 1, where one of said at least
two wall structures is an inner wall structure having a fixed
position and another of said at least two wall structures is an
outer wall structure being movable, wherein the floor is attached
to said outer wall structure.
5. The apparatus according to claim 1, where said two wall
structures have the geometry of an inner cylinder and an outer
cylinder.
6. The apparatus according to claim 1, where said two wall
structures have the geometry of an inner circular cylinder and an
outer circular cylinder.
7. The apparatus according to claim 1, comprising a third wall
structure for reducing internal unused volume for the
three-dimensional object of said build compartment.
8. The apparatus according to claim 1, comprising a mechanism for
emptying loose powder from said build compartment.
9. The apparatus according to claim 1, comprising a device for
cooling of said build compartment.
10. The apparatus according to claim 1, comprising a device for
heating of said build compartment.
11. The apparatus according to claim 1, where said
three-dimensional object is manufactured layer by layer from said
powder.
12. The apparatus according to claim 1, where said
three-dimensional object is manufactured by additive manufacturing.
Description
BACKGROUND
This invention relates to an additive manufacturing machine for
producing a three-dimensional object from a granular material, more
specifically a powder material, by consolidation of the powder
material layer by layer in a powder bed. Consolidation can be
carried out by various means, for example fusion or sintering with
an energy beam or bonding by binder jetting.
DESCRIPTION OF RELATED ART
Presently available powder bed additive manufacturing machines
normally have a movable table for lowering the consecutively built
three-dimensional object inside a build compartment during the
manufacturing process. To prevent leakage of powder, it is common
practice to have a compressible sealing material, for example an
elastomer, a textile felt or a braided rope, between the movable
table and the build compartment surrounding the powder and the
three-dimensional object. In such machines there are often problems
with powder leakage due to a defective seal. This could for example
be due to challenging environment in the machine such as friction,
heat, vacuum, radiation, etc., causing the seal material to degrade
and lose its sealing properties. An additional problem is that the
powder and three-dimensional object could be contaminated by debris
from the degraded seal. Such contamination could degrade the
material properties of the three-dimensional object and it could
also make it impossible to reuse excess powder from the build
compartment.
SUMMARY OF THE INVENTION
This invention relates to an apparatus for manufacturing a
three-dimensional object from powder, comprising a build
compartment having at least two wall structures movable in relation
to each other, said wall structures are at least partly overlapping
in the movable direction, providing a variable volume for enclosing
powder.
In embodiments, said at least two wall structures are vertical wall
structures.
In embodiments, said at least two wall structures are inner and
outer wall structures.
In embodiments, said inner wall structure has a fixed position and
said outer wall structure being movable, wherein a floor is
attached to said outer wall structure.
In embodiments, said two wall structures have the geometry of an
inner cylinder and an outer cylinder.
In embodiments, said two wall structures have the geometry of an
inner circular cylinder and an outer circular cylinder.
In embodiments, the apparatus comprises a third wall structure for
reducing internal unused volume for the three-dimensional object of
said build compartment.
In embodiments, the apparatus comprises a mechanism for emptying
loose powder from said build compartment.
In embodiments, the apparatus comprises a device for cooling of
said build compartment.
In embodiments, the apparatus comprises a device for heating of
said build compartment.
In embodiments, said three-dimensional object is manufactured layer
by layer from said powder.
In embodiments, said three-dimensional object is manufactured by
additive manufacturing.
The scope of the invention is defined by the claims, which are
incorporated into this section by reference. A more complete
understanding of embodiments of the invention will be afforded to
those skilled in the art, as well as a realization of additional
advantages thereof, by a consideration of the following detailed
description of one or more embodiments. Reference will be made to
the appended sheets of drawings that will first be described
briefly.
BRIEF DESCRIPTION OF DRAWINGS
In the description of the invention references is made to the
following figures, in which:
FIG. 1A shows, in a schematic section view, powder flowing out from
an opening in a container, creating a stationary powder slope with
an angle of repose a. No continuous flow of powder from the opening
in the container.
FIG. 1B shows, in a schematic section view, a liquid flowing out
from an opening in a container. In contrast to FIG. 1A, the liquid
will continue to flow until the container is empty.
FIGS. 2A and 2B show, in a schematic section view, a preferred
embodiment of the invention. FIG. 2A represents an early stage of
the manufacturing process and FIG. 2B represents the final stage
where the manufacturing has been finished.
FIGS. 3A and 3B show, in a schematic section view, an embodiment of
the invention. FIG. 3A represents an early stage of the
manufacturing process and FIG. 3B represents the final stage where
the manufacturing has been finished.
FIGS. 4A and 4B show, in a schematic section view, an embodiment of
the invention. FIG. 4A represents an early stage of the
manufacturing process and FIG. 4B represents the final stage where
the manufacturing has been finished.
FIGS. 5A and 5B show, in a schematic section view, an embodiment of
the invention. FIG. 5A represents an early stage of the
manufacturing process and FIG. 5B represents the final stage where
the manufacturing has been finished.
FIGS. 6A and 6B show, in a schematic section view, an embodiment of
the invention. FIG. 6A represents an early stage of the
manufacturing process and FIG. 6B represents the final stage where
the manufacturing has been finished.
Embodiments of the present disclosure and their advantages are best
understood by referring to the detailed description that follows.
It should be appreciated that like reference numerals are used to
identify like elements illustrated in one or more of the
figures.
DESCRIPTION AND DISCLOSURE OF THE INVENTION
To facilitate the understanding of this invention, a few terms are
defined below.
The term "powder" refers in this context to any type of granular
material, regardless of size, shape and composition of the
individual particles or granules that are the constituents of the
granular material.
The term "three-dimensional object" refers in this context to any
type of three dimensional preform, or any combination of
three-dimensional preforms, that can be shaped from powder in an
additive manufacturing machine. It is understood that the
three-dimensional object, such as it comes out from the additive
manufacturing machine, may require one or several steps of further
processing to reach a state where it is ready for its intended
use.
The term "manufacturing" refers in this context solely to the
process of bonding powder particles together into a
three-dimensional object in an additive manufacturing machine. The
bonding can be carried out for example by fusion or sintering with
an energy beam, or by adding a liquid binding agent. Thus, in this
context, the term "manufacturing" does not imply that the
three-dimensional object has reached its final state. The
three-dimensional object may require one or several steps of
further processing to reach a state where it is ready for its
intended use.
The invention being disclosed here is based on the understanding
that powder materials cannot flow upwards and hence a sealing can
be achieved by side walls of a container overlapping each other.
Powders can support shear stresses unlike gases and liquids. When
allowing powder to flow from an opening near the bottom of a
container, the powder present an angle of repose a that is greater
than zero degrees, as depicted in FIG. 1A. This means that the
supporting shear forces internally between the powder grains in the
powder will create a powder slope and the powder will stop flowing
out from the container when the powder slope has reached the upper
edge of the opening. A liquid, on the other hand, has normally an
angle of repose equal to zero degrees, as depicted in FIG. 1B. The
liquid does not create a stationary slope preventing it from
flowing out. Thus, the liquid will continue to flow until the
container is empty.
The purpose of this invention is to provide a self-sealing build
compartment that does not contaminate the powder, is easy to clean
and works for many different powder materials. This purpose is
achieved by the apparatus defined in the independent claim. The
dependent claims contain advantageous embodiments, further
developments and variants of the invention.
An embodiment of this invention is shown in FIGS. 2A and 2B. An
apparatus is provided having a build compartment for containing
powder and the manufactured three-dimensional object. The build
compartment has a first fixed vertical inner wall structure 203 and
a second outer vertical wall structure 204 movable downwards to
expand the volume of said build compartment, thus creating a
variable volume. The variable volume is used for expanding the
build volume by lowering the floor 208 successively during the
manufacturing of the three-dimensional object 206 layer by layer.
The movable part of said build compartment is constituted of the
second wall structure 204 and a floor 208 attached to said second
wall structure 204 with a leak free connection for preventing
powder to flow out from the compartment. When the second wall
structure 204 and the floor 208 is moved downwards in relation to
the first wall structure 203, the volume of the build compartment
will expand. The first 203 and second 204 wall structures can be
formed with a suitable cross section in the horizontal plane, for
example circular or square cross section, for forming the volume of
the build compartment. The volume of the build compartment is
formed by the first wall structure 203 and the floor 208 for
limiting the powder and object 206 from escaping from the build
compartment. The compartment has an open end, at the top, providing
a powder surface for melting a powder layer with an energy beam 207
and successively building of a three-dimensional object 206. During
manufacturing of the three-dimensional object 206, said movable
part of said build compartment is being lowered layer by layer. The
first 203 and second 204 vertical walls are arranged substantially
parallel to each other and overlapping each other in the vertical
direction and being spaced with a distance creating a gap between
the first 203 and second 204 walls in the horizontal direction. The
distance of said gap could preferably be in the range 0.3-3.0 mm
for powder sizes commonly used in powder bed additive manufacturing
systems. Even if there is a horizontal gap, the powder will be
prevented from flowing out from said build compartment due to the
fact that powder cannot flow upwards. When said movable part
successively is lowered, the powder will be prevented from flowing
out from the compartment due to the overlap between the first 203
and second 204 vertical walls creating a vertical distance between
the lower edge of said first wall structure 203 and the upper edge
of said second wall structure 204. To avoid powder from flowing out
from the build compartment, the lower most position of the movable
part is limited to a position where the first 203 and second wall
structure 204 will prevent the powder from flowing out from the
build compartment.
For clarity and completeness, FIGS. 2A and 2B also show a schematic
powder distribution system comprising a powder container 202, from
which small portions of powder are provided, a powder distributor
201 that moves over the powder bed and a powder table 205 for
distribution of a thin layer of powder. It should be pointed out
that powder distribution systems can be embodied in many different
ways and the schematic representation in FIGS. 2A and 2B is for
illustration only. The powder distribution system will not be
further discussed, since it is irrelevant for the function of the
present invention.
In another embodiment, shown in FIGS. 3A and 3B, the build
compartment is telescopic with multiple wall structures 303, 304,
307 sliding into one another. Three wall structures 303, 304, 307
are depicted in FIGS. 3A and 3B, but a larger number of wall
structures may also be used. The function of this embodiment is
identical with the previous one, with the added advantage that a
three-dimensional object 206 with increased height can be
manufactured with a reduced total height of the build
compartment.
In yet another embodiment, shown in FIGS. 4A and 4B, the movable
part consists of a second wall structure 404, a third wall
structure 409 and a floor 208 connected to each other. When the
movable part is provided with a third vertical wall structure 409
it is possible to position the floor 208 higher up in the build
compartment. In this way there will be less powder needed to fill
up the compartment before starting the manufacturing of the
three-dimensional object 206 since elsewise the powder distributor
201 need to fill the unused volume of the build compartment with
powder before the object 206 can start to be manufactured. When a
third wall structure 409 is provided an unused dead volume of
powder will be avoided below the manufactured object. In this case
there will be two horizontal gaps between the first 409, second 403
and third 404 vertical walls. Both the second 404 and the third
wall structure 409 are at least partially overlapping the first
wall structure 403 in the movable direction. By providing a third
wall structure 409 an unused powder volume can be avoided by
reducing the internal volume of the build compartment. Hence a
larger portion of the build compartment is used by the
three-dimensional object and internal unused volume of said build
compartment is reduced.
In yet another embodiment, shown in FIGS. 5A and 5B, the outermost
wall structure 504, of the movable part, is lifted by a lifting
mechanism 510 when the movable part reaches its lowermost position.
By this mechanism the second wall structure 504 is separable, from
the third wall structure 409 and the floor 208 for emptying loose
powder from the build compartment. In this way, loose powder can be
emptied out from the build compartment by gravitational force,
immediately after the manufacturing is finished. This makes it
easier to clean out excess powder when the additive manufacturing
machine is prepared for the next build. A further advantage of
immediate powder removal is that cooling rate of the
three-dimensional object 206 is improved, since any remaining
powder surrounding the three-dimensional object 206 will act as a
heat insulator.
In yet another embodiment, shown in FIGS. 6A and 6B, the floor 208
is designed as a thick block of a material with good thermal
conductivity, for example copper or another metal. Inside the floor
208, there is a device 611 for cooling or heating. For cooling,
said device 611 can be an internal channel filled with a flowing
cooling media such as cold water, oil or air. For heating, said
device 611 can be an internal channel filled with a flowing heating
media such as hot oil. Alternatively, for heating, said device 611
can be an internal electric heating device. The advantage of the
embodiment in FIGS. 6A and 6B is that said massive floor 208 acts
as a heat buffer for the build compartment, helping to maintain a
steady temperature throughout the manufacturing process.
Furthermore, said heating/cooling device 611 can be used to
regulate the build temperature in order to stabilize the
manufacturing process and to optimize the quality of the
three-dimensional object. Furthermore, said device 611 can be used
to improve the cooling rate immediately after the manufacturing is
finished.
For some embodiments, the movable part of the build compartment may
at its lowermost position, FIGS. 2B, 4B and 6B, come to a position
with negative overlap in the vertical direction between the
vertical wall structures. Even a small negative overlap can still
prevent powder from flowing out, due to the angle of repose of the
powder. However, it is desired to keep a positive overlap between
the vertical wall structures to have a margin to the position when
powder will flow out from the compartment.
These different embodiments should only be considered as examples
not limiting the possible different geometries of the build
compartment. The embodiments can also be employed in various
combinations with one another.
* * * * *